In recent years, touch technology has been universally used in daily work and life. Since a user may touch a touch screen by hand or with other object to input information, the dependency of the user on other input equipment (such as keyboard, mouse and remote controller) is reduced and even eliminated, and the operation of the user is facilitated.
FIG. 1 shows a schematic diagram of a partial structure of a touch point detecting circuit of the existing inductive touch screen. The touch point detecting circuit 11 includes a plurality of inductive units, and each inductive unit can represent a position coordinate on the touch screen, wherein each inductive unit 12 includes a spiral coil with two connecting ends. As known from FIG. 1, each inductive unit 12 is connected to an identical input connecting terminal 13 through an input signal line 13a, and each inductive unit 12 has an output signal line 14a connected to a different output connecting terminal 14 respectively. Accordingly, when the user simultaneously touches different points of the touch screen, the touch screen can determine the positions of multiple touch points through detecting an induced current generated by an inductive unit 12 corresponding to each touch point, so as to achieve multi-point touch. However, each inductive unit is provided with one output connecting terminal, a large amount of space may be occupied for wiring, and the total space of a panel of the touch screen is limited, so the space occupied by the inductive units is reduced, the quantity of the inductive units is also limited, then the position coordinates on the touch screen are reduced, thus the detection precision of the touch points is relatively low.
FIG. 2 shows a schematic diagram of a touch point detecting circuit of another existing inductive touch screen. The touch point detecting circuit includes a plurality of inductive units 21 likewise, and each inductive unit 21 includes a spiral coil, wherein the inductive units 21 of a same row are jointly connected to a row detecting circuit 22 of this row, and the inductive units 21 of the same column are jointly connected to a column detecting circuit 23 of this column. Compared with the above-mentioned solution, the space occupied for wiring is obviously reduced, so the quantity of the inductive units 21 is increased, the position coordinates on the touch screen are also increased, thus the detection precision of the touch points is relatively high. However, just due to this structure, when the user simultaneously touches different points on the touch screen, the row detecting circuits 22 and the column detecting circuits 23 corresponding to these touch points will find a position where the inductive unit 21 has the maximum induced current value by comparing the magnitude of the current values of multiple induced currents generated by each inductive units 21, and determines the position as a unique touch point, so this solution is merely applicable to single-point touch and produces misjudgment under the condition of multi-point touch.
An inductive touch screen capable of detecting the touch points with relatively high precision and realizing multi-point touch does not exist at present.